An organic light-emitting display (OLED) performs display using a self-lighting emission property of an organic semiconductor material. As compared with a liquid crystal display, the organic light-emitting display does not need backlight and may effectively reduce a thickness of a display screen. Usually, in OLED a pixel array comprised of sub-pixels is disposed in a display region of the organic light-emitting display. Each sub-pixel comprises an organic light-emitting diode, which is driven by a pixel driving circuit to emit light.
A current type of pixel driving circuit may comprise a driving transistor, and the driving transistor provides light-emitting current to the organic light-emitting diode under control of a light-emitting control signal. Usually, the light-emitting current of the organic light-emitting diode is relevant to a threshold voltage Vth of the driving transistor, but the threshold voltage Vth of the driving transistor undergoes drift (namely, “threshold drift”) due to factors such as process or aging after long-term use, so the luminance of the organic light-emitting diode exhibits a poor accuracy. Furthermore, an amount of drift of the threshold voltage of different organic light-emitting diodes might be different from one another, and display luminance of the sub-pixels deviates apparently so that display uniformity of images is undesirable.